This invention relates to control of hydraulically operated apparatus, and in particular to a hydraulic valve assembly having a positionable valve spool disposed in a housing bore, with the valve spool being movable into four positions, each of which provides a different function in combination with other elements of the valve assembly.
The invention is particularly adapted for operating the deck and mowing motor of a mowing apparatus, although other uses of the valve assembly according to the invention can be envisioned and will be apparent. Given the nature of the invention, it is described in relation to a mowing apparatus.
In a hydraulically-operated mowing apparatus, the mowing deck is raised and lowered as required. Typically the mowing motor is operated only when the deck is lowered and the mowing blades are therefore oriented at a proper elevation for grass cutting. Hydraulic pressure is used for raising the deck as well as operating the mowing motor. There are therefore four basic connections involved, one bringing pump pressure to the mowing apparatus for use, one returning expended hydraulic fluid to a tank reservoir, one to the deck raising and lowering cylinder or cylinders, and one to the motor on the deck for rotating the mowing blades.